Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01G—WEIGHING
  • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
  • G01G19/08—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for incorporation in vehicles
  • G01G19/086—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for incorporation in vehicles wherein the vehicle mass is dynamically estimated

Definitions

• the present invention relates to a transport means provied with a load meter.
• Applications are in the transport world, people transport and in other vehicles possibly provided with trailers, for the purpose of determining the loading thereof.
• Known from EP-0285689-A1 is a device for determining the weight of a load transported by an agricultural machine.
• the known device makes use of a speed sensor which measures the relative acceleration between an initial speed and a final speed compared to the acceleration measured with a calibrated weight.
• Such a known device is however relatively complicated and only functions properly on a flat road.
• the present invention has for its object to provide a transport means wherein the above stated drawbacks are obviated and the load can be measured in a simpler manner.
• the present invention provides for this purpose a transport means provided with a load meter, comprising: - a gravitation sensor; - a processor coupled operatively to the gravitation sensor for processing the data received from the sensor; - input/output means coupled operatively to the processor for input and output of data.
• a transport means can determine its load during use by means of the built-in load meter. The power, acceleration etc. can also be determined.
• the sensor measures gravitational forces in a first direction and in a second direction, which second direction is substantially perpendicular to the first direction. The meter can thus also operate when the transport means is situated on an inclining ground surface.
• the transport means has a longitudinal axis, wherein the first and the second direction lie roughly in the plane of the longitudinal axis. Accuracy is thus found to be greater.
• the present invention provides a method for measuring the load of a transport means, comprising the steps of: - arranging in the transport means a load meter comprising a gravitation sensor, a processor coupled to the gravitation sensor and input/output means coupled to the processor; - accelerating the unladen transport means at full power in order to perform a calibration measurement; - storing the calibration measurement in a memory of the processor; - accelerating the laden transport means at full power in order to perform a measurement; and - determining the loading of the transport means from the measurement and the calibration measurement.
• the loading of a transport means can be determined in relatively simple manner, as well as the initial and final speed of a measurement, the path covered, the path covered per unit of time, the acceleration and the power.
• the gravitation sensor measures the gravitational force in a first and in a second direction which are roughly perpendicular to each other.
• the sensor is hereby for instance suitable for measurements wherein the transport means is on an inclining surface.
• the method comprises of measuring the position of the acceleration sensor relative to the transport means after arranging thereof, which position is stored in the memory of the processor for the purpose of compensating measurements.
• the sensor can thus be arranged in the transport means at a random orientation since a compensation factor can be determined, so that the method and the load meter are more user-friendly.
• the load meter measures, prior to a measurement, the angle at which the transport means is situated in order to compensate the measurement. Compensation is thus made for an inclining ground surface, whereby the measurements are more accurate and the load meter is more user-friendly that known meters.
• - figure 1 shows a side view of a transport means according to the present invention
• - figure 2 shows a schematic representation of the load meter according to the present invention in a first preferred embodiment
• - figures 3a to 3c show a cut-away side view of an acceleration sensor according to the present invention in three situations of use
• - figures 4a to 4c show the graphs of the temperature gradient associated with figures 3a to 3c
• - figure 5 shows a graph of the acceleration of the transport means in time and two curves measured at different loads
• - figure 6 shows a block diagram of the acceleration sensor according to the present invention.
• the present invention provides a transport means provided with a device 1 for measuring a number of static and dynamic properties.
• the transport means is preferably a vehicle such as a truck 2, but can also be a ship or aircraft.
• Device 1 can determine the initial and final speed, the path covered, the path covered per unit of time, torque, the acceleration, power and loading of the transport means.
• device 1 is particularly suitable for freight vehicles such as the shown truck 2 (fig. 1) or similar vehicles such as passenger cars possibly provided with a trailer, agricultural vehicles or load-carrying vehicles used in a factory.
• Truck 2 comprises a number of wheels 3 with which it is positioned on a random ground surface 4.
• device 1 for measuring all the above stated vehicle properties comprises a sensor 10 for measuring a gravitational force in two or more directions.
• Sensor 10 is coupled operatively to a processor 11 for processing measurement data from sensor 10.
• Processor 11 is provided with a memory and is further coupled to input/output means 12 which comprise a screen 13 for displaying data and a number of keys 14 for inputting data (fig. 2) .
• Sensor 10 for measuring gravitational forces in two mutually perpendicular directions x and y comprises a housing 20 which comprises in side view a cylindrical part 22 constructed from a silicon substrate on which control electronics are arranged.
• a hemispherical chamber 24 Arranged on substrate 22 is a hemispherical chamber 24 which is filled with a gas.
• a recess 26 which is separated from chamber 24 by a temperature sensor 28 and which has a relatively low air pressure so as to prevent heat transfer.
• a heating element 30 is arranged against the temperature sensor for heating the gas situated in chamber 24 (fig. 3a) .
• the heat source 30 is arranged centred relative to chamber 24.
• Temperature sensors (32, 33, 34 and 35) for measuring the temperature are arranged at equal distances from heating element 30 on four sides thereof (fig. 5) .
• the temperature sensors are preferably formed by thermocouples constructed from aluminium and polysilicon.
• Gravitation sensor 10 is a biaxial movement measuring system based on heat transfer by natural convection in the gas of chamber 24.
• the sensor measures the changes in this convection caused by accelerations or a gravitational force in x-direction or in y- direction.
• this device is the same as known acceleration meters based on the inertia of a calibration mass. If sensor 10 does not undergo any acceleration, the temperature gradient will be symmetrical relative to heat source 30, so that the temperature at the four thermocouples 32-35 is the same, so that they output the same voltage.
• the temperature gradients associated with figures 3a to 3c are shown in figures 4a to 4c, wherein the vertical axis represents the temperature T and the horizontal axis represents the distance s relative to heat source 30.
• Figures 3a and 4a show the situation wherein heating element 30 is switched off.
• the sensor When the sensor is switched on and does not undergo any acceleration, the sensor is in the situation shown in figure 3b.
• a cloud of heated gas 40 lies symmetrically around heating element 30 and produces the temperature gradient shown in figure 4b.
• cloud 40 When the undergoes an acceleration, cloud 40 will be subjected to a displacement due to the difference in density of the gas (fig. 3c) , resulting in an asymmetrical temperature gradient (fig. 4c) .
• the difference ⁇ in a measured temperature and the resulting difference in voltage between two temperature sensors located opposite each other is proportional to the acceleration in the direction of the axis by the pair of thermocouples.
• sensor 20 is equipped with two pairs of thermocouples, i.e. 32/34 and 33/35, the sensor can measure the acceleration on the x-axis and on the y- axis .
• the device according to the present invention operates as follows. It is important when the device is fitted in vehicle 2 that the vehicle is standing on a flat, non-inclining ground surface. The device is mounted at a random position in the vehicle. For the greatest possible accuracy, the x-axis and y- axis lie roughly in the plane formed by the length and width directions of the vehicle. After the device is switched on, the processor will determine the position of the sensor relative to the ground surface on the basis of the gravitational force exerted on the heated gas cloud 40 by the force of gravity.
• the acceleration a is shown on the vertical axis and the time t on the horizontal axis.
• the data determined during this calibration measurement are the initial and final speed, the path covered, the path covered per unit of time, the acceleration, the power of the vehicle and the work produced.
• the device can be used as load meter. This takes place by performing a similar measurement wherein the laden vehicle is put into the same gear, the first or the second, as during the calibration measurement.
• processor 11 checks the position in which the sensor 10 is situated in the ab- plane and uses this information to correct the performed measurement. When the vehicle begins to move, full throttle is again applied. During acceleration at full throttle the acceleration is measured and this is plotted as curve 52 in figure 5, wherein t2 is the time at which maximum acceleration is reached.
• the mass m of the vehicle is calculated from:
• f (a) is a correction function.
• f (a) will be a constant. It may however occur that in some vehicles this function depends on the acceleration. This is then generally a quadratic function.
• a gravitation sensor is for instance used as supplied by MEMSIC under type number MXA2312U. Such a sensor has a noise sensitivity with which accelerations of less than 0.01 m/s 2 can be measured. The frequency response is about 30 Hz and can be expanded to more than 160 Hz.
• the sensor comprises chamber 28 with heating element 30 and the thermocouples 32 to 35 which are connected to two amplifiers 60, 62 for the x-axis and y-axis respectively.
• the sensor further comprises a heating control element 64, low-pass filters 66, 68 and a correction element 70 to enable advance correction for variations.
• switch element 72 it is possible to choose between an internal clock 74 or an external clock to be connected to contact point 76.
• the sensor further has a continuous self-test 78 and provides a reference voltage at 80, 81, and a temperature sensor 82 for measuring the external temperature is incorporated with output 84.
• a processor that is used is for instance the Micro Converter with 12-bit ADCs and DACs as supplied by Analog Devices under type number AduC832.
• the present invention is not limited to the above described preferred embodiment thereof, wherein many modifications can be envisaged, but the invention is defined by the scope of the appended claims.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Testing Or Calibration Of Command Recording Devices (AREA)

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• 2004
  • 2004-03-26 NL NL1025834A patent/NL1025834C2/nl not_active IP Right Cessation
• 2005
  • 2005-03-24 EP EP05729412A patent/EP1735602A1/de not_active Withdrawn
  • 2005-03-24 WO PCT/NL2005/000225 patent/WO2005093383A1/en active Application Filing

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